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Authen::Krb5::Simple - Basic user authentication using Kerberos 5


  use Authen::Krb5::Simple;

  # Create a new Authen::Krb5::Simple object using
  # the system default realm.
  my $krb = Authen::Krb5::Simple->new();

  # Authenticate a user.
  my $authen = $krb->authenticate($user, $password);

  unless($authen) {
      my $errmsg = $krb->errstr();
      die "User: $user authentication failed: $errmsg\n";

  # Get the current default realm.
  my $realm = $krb->realm();

  # Set the current realm

  # Create a new object pointing to another realm.
  my $alt_krb = Authen::Krb5::Simple->new(realm => 'OTHER.REALM');


The Authen::Krb5::Simple module provides a means to authenticate a user/password using Kerberos 5 protocol. The module's authenticate function takes a username (or user@kerberos_realm) and a password, and authenticates that user using the local Kerberos 5 installation. It was initially created to allow perl scripts to perform authentication against a Microsoft Active Directory (AD) server configured to accept Kerberos client requests.

It is important to note: This module only performs simple authentication. It does not get, grant, use, or retain any kerberos tickets. It will check user credentials against the Kerberos server (as configured on the local system) each time the authenticate method is called.



    The new method creates the Authen::Krb5::Simple object. It can take an optional argument hash. At present the only recognized argument is realm.

    If no realm is specified, the default realm for the local host will be assumed. Once set, the specified realm will be used for all subsequent authentication calls. The realm can be changed using the realm function (see below).


    Using the default realm:

      my $krb = Authen::Krb5::Simple->new();

    specifying a realm:

      my $krb = Authen::Krb5::Simple->new(realm => '');


authenticate($user[@realm], $password)

    the authenticate method takes the user (or user@realm) and a password, and uses kerberos 5 (the local systems installation) to authenticate the user.

    if the user/password is good, authenticate will return a true value. Otherwise, a false value is returned and the error code is stored in the object.

      if($krb->authenticate($user, $pw)) {
          print "$user authentication successful\n";
      } else {
          print "$user authentication failed: ", $krb->errstr(), "\n";

realm( )


    The realm method is used to set or get the current default realm. If an argument is passed to this method, the default realm is set to that value. If no argument is supplied, the current realm is returned.


    The errstr method will return the error message from the most recent authentication call.


    The errstr method will return the krb5 error code from the most recent authentication call. This value will not be very useful. Use the errstr method to get a meaningful error message.


This version of Authen::Krb5::Simple does not support null or empty passwords. If you pass an undefined value or empty string ('') as a password, authenticate return false and set the error to indicate that null or empty passwords are not supported.


Damien S. Stuart, <>


perl, Kerberos5 documentation.